Breech bolt operating mechanism



Sept. 19, 1961 R. s. ROBINSON BREECH BOLT OPERATING MECHANISM 4 Sheets-Sheet 1 Filed Sept. 24, 1952 ATTOR N EYS Sept. 19, 1961 R. s. ROBINSON BREECH BOLT OPERATING MECHANISM 4 Sheets-Sheet 2 Filed Sept. 24, 1952 3H4) cm/tov ATTO R N EYS Sept. 19, 1961 R. s. ROBINSON 3,000,267

BREECH BOLT OPERATING MECHANISM Filed Sept. 24, 1952 4 Sheets-Sheet 3 ATTOR N EYs Sept. 19, 1961 Filed Sept. 24, 1952 R. S. ROBINSON BREECH BOLT OPERATING MECHANISM 4 Sheets-Sheet 4 7 1 LZZ 7| :2 l

swam low ATTOR N EYS 3,000,267 BREEQH BOLT OPERATING MECHANISM Russell S. Robinson, Short Beach, Conn. (124 Via Yella, Lido Isle, Newport Beach, Calif.) Filed Sept. 24, 1952, Ser. No. 311,215 19 Claims. (Cl. 89-169) This invention relates to the means by which the forward driving or recuperator force is applied to the recoiling masses in recoil operated firearms, its object being to achieve a short cyclic firing period and smooth recoil reaction.

In known recoil-operated firearms of the type in which the breech bolt is operated by a mechanism which interacts between the gun casing and the barrel in order first to accelerate and then to decelerate the breech bolt with respect to the barrel during each recoil and runout stroke or movement of the barrel, the recuperator is mounted so as to bear forwardly on the barrel, barrel extension, or a part fixed thereto.

As the breech bolt in such firearms moves relatively to the barrel and has to move a considerably greater distance than the barrel during their respective reciprocations and as the breech bolt and part of its actuating mechanism may have a weight equal to a considerable proportion of the weight of the barrel assembly, the energy derived from barrel movement via the mechanism which is required to provide the relatively great acceleration and deceleration of the breech bolt during each of its recoil or runout movements may be such as to seriously interrupt the smooth acceleration or deceleration of the barrel during its runout or recoil respectively, thereby first lengthening the time required for the barrel stroke and correspondingly increasing the cyclic period, and secondly causing fluctuations in the net unbalanced thrust of the recuperator spring which correspondingly increases recoil vibration.

In firearms according to the invention, the recuperator is mounted so as to apply a force in a substantially forward direction on a member fixed near the fulcrum of the main operating lever of the breech bolt mechanism and is so disposed that when the barrel is in recoil, a force or couple is applied to the operating lever which tends to rotate it so as to thrust the breech bolt forward, and, as the barrel moves forward the rotation of the operating lever causes the arm of the couple to diminish to zero and then build up on the opposite side until when the barrel is fully run out the couple is tending to rotate the operating lever soas to thrust the breech bolt rearward. By this means the forwardly directed recuperator thrust is continuously applied to the barrel via the fulcrum point of the bolt-actuating lever in the barrel extension, yet is further harnessed to apply a forward acceleration to the breech bolt during the first part, and a deceleration during the latter part, of its forward movement; and -a rearward acceleration to the breech bolt during the first part, and a deceleration during the latter part, of its rearward movement.

Furthermore, in firearms according to the invention, the recuperator may be mounted so as to bear substantially forwardly on the body of a beam, one end of which is pivoted to the barrel extension and the other oscillatably fixed directly or via a connector link, to the said member fixed near the fulcrum of the main operating lever of the breech bolt mechanism, whereby part of the recuperator thrust is applied directly to the barrel extension and the remainder to the fulcrum in the barrel extension via the said member to the same end as above described, except that a smaller proportion of the recuperator force is available for bolt acceleration purposes.

States Patent "ice In the accompanying drawings:

FIG. 1 is a vertical section through the barrel center line of the breech end of a firearm of the type which fires during runout at a point close to its forward limit of movement, the barrel being shown in full recoil;

FIG. 2 is a similar section of the same firearm, the barrel being shown in full runout (battery position);

FIG. 3 is a similar view showing an intermediate position of the parts;

FIG. 4 is a diagrammatic section on line 44 of FIG. 1;

FIG. 5 is a view similar to FIG. 1 showing a modified form of my invention, the parts being shown in full recoil position;

FIG. 6 is a similar view showing the barrel in full runout position;

FIG. 7 is a sectional view showing the parts in an intermediate position;

FIG. 8 is a transverse sectional view on line 8-8 of FIG. 5;

FIG. 9 is a longitudinal sectional view through the breech portion of the gun casing illustrating a further modified form of my invention, the parts being shown in full recoil position;

FIG. 10 is a sectional view similar to FIG. 9 showing the barrel and associated parts in full runout position;

FIG. 11 is a sectional view similar to FIG. 9 and 10 showing an intermediate position of the barrel assembly;

FIG. 12 is a transverse sectional view on line 1212 of FIG. 9; and

FIG. 13 is a transverse sectional view on line 13--13 of FIG. 11.

Referring to FIGS. 1, 2 and 3, the firearm comprises a gun frame 1, a barrel assembly including a barrel 2, and a barrel extension 3 fixed to the barrel by means of a thread 4, the assembly being slidably mounted with respect to the frame 1 by means of a ring guide 5 about the barrel, and guide lugs 6 on a part of the barrel extension which slide in slots 7 in the frame 1, the longitudinal movement of the barrel 2 and barrel extension 3 being thus limited to that shown in FIGS. 1 and 2. The firearm further comprises a breech bolt 8 which slides in oppositely facing grooves 9 in the spaced plates 3 of the barrel extension 3. A toggle link 10, one end of which is pivoted at 11 to the rear of the breech bolt 3, is pivoted at its opposite end to a forked toggle lever 12. This lever is pivoted on the barrel extension by means of pins 13, these pins being oscillatably mounted in the plates of barrel extension 3, their axes intersecting the barrel axis. 2

An opposite and continuous extension of the lever 12 is pivoted to an actuator link 14, the opposite end of which is pivoted to the gun frame 1 at 15. Upon the lever 12 is mounted a pin 16 which is oifset from its center line and which oscillatably supports a spring guide tube 17. Within the guide tube 17 slides a spring guide rod 18, the rear end of which is pivoted at 19 to the gun frame 1. The tube 17 and rod 18 are provided adjacent their pivoted ends with shoulders 20 and 21 respectively against which bear the ends of a compression spring 22 normally urging separation of these members.

The functioning of this example is such that as the barrel assembly 2 and 3 moves forward from the position shown in FIG. 1 it is accelerated by the longitudinal component of the spring 22 bearing against the barrel extension 3 via the guide tube 17, pin 16, lever 12, and fulcrum pins 13. At the same time an unbalanced couple applies a torque to the lever 12 which tends to rotate the lever 12 around its fulcrum pin 13 thus throwing the breech bolt forwards. As the barrel extension 3 moves forward and lever 12 continues to rotate under the action of link 14 assisted by the said torque, the arm of the couple becomes smaller until a point is reached when the center line of pin 16 crosses the barrel axis at which instant the arm of the couple and torque applied to the lever 12 is zero, this position of the parts being shown in FIG. 3.

Pin 16 should be so located with respect to the body of the lever 12 that it crosses the barrel axis substantially at the moment when the forward velocity of the breech bolt 8 is at its maximum. As the barrel 2 continues to run forward and the lever 12 continues to rotate, pin 16 increases its displacement with respect to the barrel axis, but on the opposite side of the barrel axis, thereby applying an increasing torque to the lever which tends to oppose its rotation and thus decelerate the breech bolt 8.

By the time the barrel extension 3 has reached the position shown in FIG. 2, at which point its forward velocity is maximum, the breech bolt 8 has been slowed down to the same velocity as the barrel assembly through the action of link 14 assisted by the said decelerating torque.

Following firing and the beginning of recoil the couple as shown in FIG. 2 applies a torque which tends torotate the lever 12 so as to accelerate the breech bolt 8 rearward. As recoil continues, and substantially at the point where the rearward velocity of the breech bolt 8 is maximum, pin 16 recrosses the barrel axis and from this point rearward the increasing displacement of pin 16 applies a torque to lever 11 which tends to decelerate the breech bolt 8 until the entire system is brought to rest in the position similar to FIG. 1.

In FIGS. 5, 6, 7 and 8 of the drawings I have shown a modified form of my invention wherein the firearm comprises a barrel assembly including a barrel 30 to which is threadedly connected a barrel extension 31 by means of thread 32, the extension comprising spaced plates 33 and 34. The barrel assembly slides longitudinally in a gun frame 35 being supported therein by a ring guide 36 around the barrel 30 and a boss 37 secured to a lug 38 on the plate 34 in the barrel extension 31 which boss slides in a slot 39 in the gun frame 35. An operating lever 40 is provided with a trunnion 41 which oscillatably fixes it to the lug 38 of the barrel extension 31, the trunnion 41 coaxially passing through the boss 37 and being rotatable therein. A breech bolt 42 which slides in grooves 43, 44 in the plates 33 and 34 is connected to the end of the lever 40 by link 45. At the opposite end of lever 40 is a fork 46 which engages over a roller 47 which is supported by a pin 48 secured in the gun frame 35. On the opposite side of the lever 40 from trunnion 41 is a boss 49 which carries a roller 50. The roller 50 operates in a transverse slot 51 at the rear end of the recuperator rod 52 which slides in a longitudinal guide hole 53 in the gun frame 35 and is urged forward by a recuperator spring 54 which is retained at the front end of the recuperator 52 by a nut 55.

The functioning of this example is such that with the barrel assembly moving from the position shown in FIG. 5, the recuperator 52, urged forward by its spring 54, thrusts the barrel extension forward via the roller 50, boss 49, and lever 40, which, in turn, acts about the truuion 41 in a manner which tends to rotate lever 40 so as to throw the bolt 42 forward, thereby reducing or overcoming the load which would otherwise have to be applied to fork 46 by the roller 47 to provide the relatively great acceleration of the bolt 42 via link 45 and lever 40.

Just after the barrel assembly has completed half its forward run, at which time the forward velocity of the breech bolt 42 is maximum, the line connecting the center of trunnion 41 with boss 49 becomes parallel with the barrel axis, as shown in FIG. 7, at which instant forward thrust but no rotating torque is applied to the lever 40 by action of the recuperator. As the barrel assembly continues to move forward, however, an increasing negative or decelerating torque is applied to lever 40 by the increasing displacement of boss 49 which becomes maximum when the barrel assembly is in forward position as shown in FIG. 6. The said decelerating torque tends to decelerate the breech bolt 42 after its maximum forward velocity station has been passed, and produce a rearward accelerating of the bolt 42 during the early part of recoil, thereby greatly reducing the duty of the fork 46 and roller 47.

Referring to FIGS. 9, 10, 11, 12 and 13, the third modification comprises a gun casing 60 and a barrel assembly comprising a barrel 61 and barrel extension 62 consisting of two spaced plates 62 and 62. This assembly is longitudinally slidably mounted in the casing 69 in guides including a ring guide 63 around the barrel 61, and an opposite pair of lugs 64 at the rear of the barrel extension 62 which slide in grooves 65 in the casing 60, the movement of the barrel being limited by the length of the grooves. A breech bolt 66 slides in sloping grooves 67 within the plates 62 and 62 of the barrel extension 62. At the rear end of the bolt 66 is oscillatably pinned a toggle link 68, the opposite end of which is pinned to the arm of a bell crank lever 69 forming a toggle with the link 68. At the fulcrum of the lever 69, a pin 70 is keyed to the lever, as shown at 70, the pin being circular so as to bear smoothly within the hole 71 in the barrel extension plates 62 and 62 The ends of pin 70 protrude beyond the outer faces of the plates and are squared and pierced to receive thereon a pair of opposite cranks 72, which are thereby locked to pin 70 by means of retainer wires 73. The outer ends of cranks 72 are oscillatably pinned to driving links 74, the opposite ends of which are pinned to the lower ends of a pair of beams 75. The upper ends of the beams 75 are oscillatably connected to the barrel extension plates 62 and 62 by means of opposite and coaxial trunnions 76 which are formed in the outer sides of the barrel extension plates. A pin 77 passes through each beam 75 near its center which carries two rollers 78 so disposed that one is on each side of each beam. Thrusting forwardly against each pair of rollers 7 8 is a recuperator piston 79, each of which is a close fit in one of two cylinders 80 which are fixed inside the gun casing one on each side of the barrel extension, in such manner that their axes are substantially parallel with the barrel axis. The forward end of each cylinder 80 is slotted with vertical slots 81 to receive one of the beams 75, and near the rear end of each cylinder is a port 82 connecting each cylinder to any suitable source of fluid pressure so arranged as to maintain a substantially constant pressure in the cylinder at all times.

At the opposite end of lever 69 is a stub lever 83, the end of which is pivoted to one end of an actuator link 84, the other end of which is pivoted to lugs constructed within the gun casing 60.

The functioning of the above example is such that with the barrel assembly recoiled as in FIG. 7 and with pressure fluid introduced into the opposite cylinders 80, the pistons 79 thrust forwardly against the beams 75 via the rollers 78 and pins 77, the beams 75 then dividing the thrust on the barrel extension 62 between the trunnions 76 and the links 74. The links 74, acting via the cranks 72, apply a combination of a forwardly directed load to the fulcrum holes 71 of the barrel extension 62, with a torque on the shaft 70 which tends to rotate lever 69 so as to accelerate the breech bolt forwardly.

At the point in the forward movement of the barrel extension when the velocity of the breech bolt 66 is maximum, as governed by the actuator 84 operating the levers 83, 69 and link 68, the center lines of the cranks 72 and links 74 come into substantial alignment whereby no torque is applied to the crank 74 and lever 69, as shown in FIG. 11.

From this point forward, however, as the lever 69 is constrained by the actuator 84 to continue to rotate, the cranks 72 are forced to continue past dead center until they reach the positions shown in FIG. 10, during which period they are under the continued influence of the recuperator acting via beam 75 and links 74, thereby applying an increasing torque which tends to decelerate the breech bolt 66 via its actuating linkage as above described. When recoil movement begins this latter torque provides an impetus for the very high rearward acceleration of the breech bolt which follows its initial recoil which begins with the same velocity as the barrel assembly.

While I have shown and described some preferred embodiments of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What I claim is:

1. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a member pivotally mounted on the barrel extension and connected to the casing and to the breech bolt to move the latter relatively to the barrel extension, and recuperator means supported by the casing and connected to, and acting upon, said member to apply, through said member, a restoring force to the barrel extension to return the barrel forwardly While rotating the member about its pivot to move the bolt to closed position.

2. A breech bolt operating mechanism for a firearm as in claim 1 wherein the connection of said pivoted member with the bolt comprises a link pivoted to said member and said link forming one member of a toggle.

3. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a member pivoted to the barrel extension intermediate the ends of the member, one end of said member being connected to the casing, recuperator means supported by the casing and engaging said member and means connecting said member to the breech bolt to initially move the latter forwardly at a speed greater than that of the barrel and decelerate the breech bolt during the latter part of its forward movement.

4. A breech bolt operating mechanism for a firearm as in claim 1, wherein said recuperator means engages said pivoted member at a point eccentric to its pivot on the barrel extension and offset from a line joining the pivot point of the member with the point on said member connected to the breech bolt.

5. A breech bolt operating mechanism for a firearm as in claim 1, wherein the movement of said pivoted member about its pivot is controlled by its connection with the casing to exert a forward accelerating force on the bolt during the first part of its advance and a rearward decelerating force on the bolt during the latter part of its advance.

6. A breech bolt operating mechanism for a firearm as in claim 1, wherein said recuperator means engages said pivoted member to exert a thrust thereon between its pivotal point on the barrel extension and the point on the lever which is connected to the bolt and forwardly of the line joining said points when the parts are in recoil position.

7. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a member pivoted to the barrel extension, recuperator means supported by the casing, and means connecting said pivoted member to the breech bolt and to the casing, and to the recuperator means to initially move the bolt forwardly at a speed greater than that of the barrel and decelerate the bolt during the latter part of its forward movement.

8. A breech bolt operating mechanism for a firearm 6 having a casing, a barreland barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a member pivoted to the bar rel extension, recuperator means supported by the casing, and means connecting the recuperating means to said pivoted member and connecting said member to the breech bolt to divide the thrust of the recuperator means into two forces, one exerting a forward thrust on the barrel extension and the other exerting a rotary torque onsaid pivoted member to advance the bolt, and the thrust of said recuperating means passing a dead center position with respect to the pivot point of said member on the barrel extension when the bolt nears battery position.

9. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a member pivoted to the barrel extension and connected to the casing, recuperator means supported by the casing, and means connecting the recuperating means to said pivoted member'and connecting said member to the breech bolt to divide the thrust of the recuperator means into two forces, one exerting a forward thrust on the barrel extension and the other exerting a rotary torque on said pivoted member to advance the bolt, and said last-named force during the latter part of the advance of the bolt exerting a decelerating force thereon.

10. A breech bolt operating mechanism for a firearm as in claim 1, wherein the rotation of said member about its pivot on the barrel extension is controlled by the connection of said member with the casing to exert a component of force on the bolt in a rearward direction during the latter part of the movement of the bolt.

11. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casingfor longitudinal sliding movement therein and a'breech bolt movably carried by the barrel extension, said mechanism including a member pivoted on the barrel extension, recuperator means carried by the casing, and means connecting said member to the casing, to the recuperator means, and to the breech bolt, so arranged that the thrust of the recuperator passes a dead-center position with respect to the pivot point of said member on the barrel extension and exerts a force on the breech bolt in a forward direction during the first part of the advancing movement and a force on the breech bolt in a rearward direction during the latter part of its movement.

12. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing having longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a lever pivoted to the barrel extension, recuperator means including a source of thrust which is so connected to said lever to exert a rotative force on the lever, means connecting said lever to the bolt, and the direction of said force applied to the lever by the recuperator means passing from one side to the other of the pivot of the lever with respect to the horizontal plane of the pivot whereby the bolt is first urged in the forward sense and then in the rearward sense during the advance of the bolt and barrel extension.

13. A breech bolt operating mechanism for a firearm as in claim 12 wherein the bolt is also urged first in the rearward sense and then in the forward sense during recoil of the bolt and barrel extension.

14. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a lever pivoted at an intermediate point thereof to the barrel extension, recuperator means supported by the casing, means connecting the breech bolt to a point on the lever at one side of the lever pivot, means connecting a point on the lever on the other side of said pivot to the casing, and means connecting said recuperator means to the lever at a point eccentric to the lever pivot and offset from the line joining the pivot with the point on the lever connected with the bolt.

15. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a lever pivoted at an intermediate point thereof to the barrel extension, recuperator means supported by the casing, means connecting the breech bolt to a point on the lever at one side of the lever pivot, means connecting a point on the lever on the other side of said pivot to the casing, and means connecting said recuperator means to the lever, said recuperator means comprising a pair of members having their adjacent ends in telescoping engagement, and a spring urging said members apart, the remote end of one member being pivoted to the casing, and the remote end of the other member being pivoted to the lever at a point such that the force exerted by the recuperator passes from one side to the other of a line through the lever pivot parallel to the barrel axis.

16. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a lever pivoted at an intermediate point thereof to the barrel extension, recuperator means supported by the casing, means connecting the breech bolt to a point on the lever at one side of the lever pivot, means connecting a point on the lever on the other side of said pivot to the casing, and means connecting said recuperator means to the lever, said recuperator means comprising a member mounted in the casing for longitudinal sliding movement, and a spring urging said member in a forward direction, and said member being connected to the lever at a point eccentric to the lever pivot to exert a rotative'component of force on the lever.

17. A breech bolt operating mechanism for a firearm having a casing, a barrel and barrel extension mounted in the casing for longitudinal sliding movement therein and a breech bolt movably carried by the barrel extension, said mechanism including a lever pivoted at one end to the barrel extension, means connecting the other end of said lever to the casing and to the bolt, recuperator means supported by the casing and acting on an intermediate part of said lever to urge the latter in a forward direction, the means connecting said lever with the bolt and casing including a pair of toggle members pivoted together, and the pivot point of said members passing a dead center position during the advance of the barrel whereby the recuperator exerts a forward accelerating force on the bolt during the first part of its advance and a rearward decelerating force on the bolt during the latter part of its advance.

18. A breech bolt operating mechanism for a firearm as in claim 17 wherein the recuperator means comprises a cylinder carried by the casing, a piston in said cylinder engaged and acting on said lever, and means to supply said cylinder with a fluid under pressure.

19. A breech bolt operating mechanism for a firearm as in claim 17 wherein the means connecting said lever with the breech bolt and easing comprises a bell crank lever pivoted to the barrel extension and connected at one end to the casing and at the other end to the breech bolt, and a toggle mechanism connecting the first-named lever with said bell crank lever.

References Cited in the file of this patent UNITED STATES PATENTS 591,155 Burgess Oct. 5, 1897 830,511 Lehmann Sept. 11, 1906 1,021,130 Brown Mar. 26, 1912 1,099,245 Fittipaldi June 9, 1914 1,985,493 Gebauer et a1 Dec. 25, 1934 2,048,395 Larsson et al. July 21, 1936 

